manipulate ambient light intensity with slider

hi guys,
I know how to manipulate light intensity when I have a light object in the scene.
I just drag&drop the object on the slider control in the UI canvas.

But how do I do that with Ambient Intensity (or ambient light)?

public void AdjustAmbientIntensity(Slider slider)
{
RenderSettings.ambientIntensity = slider.value;
}